U.S. patent number 10,266,406 [Application Number 16/011,684] was granted by the patent office on 2019-04-23 for producing high-purity chlorine dioxide gas.
The grantee listed for this patent is GuangXi University. Invention is credited to Chen Liang, Xinliang Liu, Shuangxi Nie, Chengrong Qin, Xueping Song, Shuangfei Wang, Zhiwei Wang, HongXiang Zhu.
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United States Patent |
10,266,406 |
Wang , et al. |
April 23, 2019 |
Producing high-purity chlorine dioxide gas
Abstract
A high-purity chlorine dioxide gas may use hydrogen peroxide as
a reducing agent and may use horizontal generator, evaporation
crystallizer, dryer and other devices to produce chlorine dioxide
gas (product) and sodium sulfate (by-product). Compared to the
conventional chlorine dioxide preparation system, the chlorine
dioxide reaction and the sodium sulfate crystallization are
performed in two processes. These processes are relatively separate
and independent, and continuously produce chlorine dioxide gas with
high purity and low moisture content while the by-product salt cake
is evaporated, crystallized, filtered and dried, thereby producing
sodium sulfate, without generating solid and liquid waste.
Inventors: |
Wang; Shuangfei (Nanning,
CN), Qin; Chengrong (Nanning, CN), Nie;
Shuangxi (Nanning, CN), Song; Xueping (Nanning,
CN), Liang; Chen (Nanning, CN), Liu;
Xinliang (Nanning, CN), Wang; Zhiwei (Nanning,
CN), Zhu; HongXiang (Nanning, CN) |
Applicant: |
Name |
City |
State |
Country |
Type |
GuangXi University |
Nanning |
N/A |
CN |
|
|
Family
ID: |
63204980 |
Appl.
No.: |
16/011,684 |
Filed: |
June 19, 2018 |
Foreign Application Priority Data
|
|
|
|
|
May 18, 2018 [CN] |
|
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201810482903 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C01B
11/026 (20130101); B01D 9/0059 (20130101); B01J
19/24 (20130101); B01D 9/0022 (20130101); B01J
7/02 (20130101); B01D 2257/2025 (20130101); B01D
2256/26 (20130101); B01J 2219/182 (20130101) |
Current International
Class: |
B01J
7/02 (20060101); B01D 9/00 (20060101); C01B
11/02 (20060101); B01J 19/24 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
108439341 |
|
Aug 2018 |
|
CN |
|
0612686 |
|
Aug 1994 |
|
EP |
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WO-2006033609 |
|
Mar 2006 |
|
WO |
|
Primary Examiner: Leung; Jennifer A
Attorney, Agent or Firm: LeonardPatel PC
Claims
The invention claimed is:
1. A device configured to produce high-purity chlorine dioxide gas,
comprising: a sulfuric acid pipe connected to a horizontal
generator; a hydrogen peroxide pipe joined by a sodium chlorate
pipe and connected to the horizontal generator; a first heat source
pipe connected to an inlet of the horizontal generator; a
compressed air pipe connected to an air compressor and the
horizontal generator, wherein the horizontal generator connected to
a mother liquor discharge tank via a reaction liquid discharge pipe
or a mother liquor discharge pipe, the mother liquor discharge tank
connected with a mother liquor lower circulating pipe by way of an
inlet and outlet pipe of a crystallizer feed pump, and the mother
liquor lower circulating pipe and an upper circulating pipe are
connected to an evaporation crystallizer, a heater and a
circulating pump; a mother liquor tank connected to the evaporation
crystallizer and the horizontal generator through an inlet and
outlet pipe of a first mother liquor extraction pump and an inlet
and outlet pipe of a mother liquor return pump; a second heat
source pipe connected to an inlet pipe of the heater; and a
filtration unit connected to the mother liquor lower circulating
pipe through an inlet and outlet pipe of a feed pump and a filtrate
pipe to form a circulation loop and the filtration unit connected
to a dryer via a salt cake discharge pipe.
2. The device of claim 1, wherein the mother liquor discharge tank
and the mother liquor tank are situated between the horizontal
generator and the evaporation crystallizer to separate the
horizontal generator and the evaporation crystallizer, and the
mother liquor discharge tank and the mother liquor tank are
configured to buffer, so that device operates continuously and
smoothly.
3. The device of claim 2, wherein the mother liquor discharge tank
equipped with the crystallizer feed pump is connected with the
horizontal generator and the mother liquor lower circulating pipe
by way of the reaction liquid discharge pipe and the inlet and
outlet pipe of the crystallizer feed pump to form an inlet channel
for the reaction liquid of the horizontal generator entering into
the evaporation crystallizer, the mother liquor tank equipped with
a mother liquid second mother liquor extraction pump and mother
liquor return pump is connected to the evaporation crystallizer and
the horizontal generator by way of an inlet and outlet pipe of the
second mother liquor extraction pump and the inlet and outlet pipe
of the mother liquor return pump to form a return channel for a
supernatant liquid of the evaporation crystallizer returning to the
horizontal generator.
4. The device of claim 3, wherein the evaporation crystallizer, the
heater and the circulating pump are connected in series via the
mother liquor lower circulating pipe and the upper circulating pipe
to form a circulation loop for heating, evaporation and
crystallization.
5. The device of claim 4, wherein the filtration unit configured
with the feed pump is connected with the dryer by way of the
filtrate pipe, the salt cake discharge pipe and the mother liquor
lower circulating pipe to form a filtrate liquid return channel and
salt cake treatment channel.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of, and priority to, Chinese
Patent Application No. 201810482903.6, filed on May 18, 2018. The
subject matter thereof is hereby incorporated herein by reference
in its entirety.
FIELD
The present invention generally relates to chlorine dioxide
preparation, and more particularly, to a process, system, and
apparatus for producing high-purity chlorine dioxide gas.
BACKGROUND
Chlorine dioxide (ClO2) is a yellow orange gas at normal
temperature and pressure and has an irritating and spicy taste
similar to a mixture of chlorine and ozone. The boiling point is
11.degree. C., the freezing point is -59.degree. C., and the
gaseous density is 3.09 g/m.sup.3 at 11.degree. C. Gaseous
ClO.sub.2 is unstable. Exposure of gaseous CIO.sub.2 to light or
organic matter at high concentration will cause it to decompose
violently and produce oxygen and chlorine. Normally it must be
produced at the mill near its point of application. It is more
stable when diluted to lower than 12% volume content with air or
steam at atmospheric temperature or in the state of a
low-temperature water solution. ClO.sub.2 is a strong oxidizer and
can be used as a bleaching agent for pulp and textiles, and as
water treatment agent, new air purifying freshener, and a
disinfection, sterilizing, deodorizing agent for food, epidemic
prevention, hygiene, etc.
At present, the main methods of producing chlorine dioxide include
the methanol method and the integrated method. The methanol method
uses methanol, sulfuric acid, and sodium chlorate as raw materials,
and a vertical generator is used to produce chlorine dioxide. The
chlorine dioxide product has a large moisture content of up to 80%
(w/w) or more, and contains a small amount of chlorine. The
integrated method uses hydrochloric acid and sodium chlorate as raw
materials and either a vertical generator or horizontal generator
can be used, but the chlorine dioxide gas contains a lot of
chlorine, and the molar ratio of chlorine dioxide to chlorine is
2:1. For the use areas with high purity requirements (such as
sodium chlorite preparation, food and medicine area, etc.), the
purity of chlorine dioxide produced by the above two preparation
methods cannot meet the use requirements.
In addition, chlorine dioxide product produced by common industrial
chlorine dioxide preparation device are pumped to the final use
areas in the form of low-temperature chlorine dioxide solution, not
supplied in the form of gas.
Accordingly, an improved process and apparatus for producing
high-purity chlorine dioxide gas may be beneficial.
SUMMARY
Certain embodiments of the present invention may provide solutions
to the problems and needs in the art that have not yet been fully
identified, appreciated, or solved by conventional chlorine dioxide
preparation technologies. For example, some embodiments pertain to
a process and apparatus for producing high-purity chlorine dioxide
gas.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the advantages of certain embodiments of the
invention will be readily understood, a more particular description
of the invention briefly described above will be rendered by
reference to specific embodiments that are illustrated in the
appended drawings. While it should be understood that these
drawings depict only typical embodiments of the invention and are
not therefore to be considered to be limiting of its scope, the
invention will be described and explained with additional
specificity and detail through the use of the accompanying
drawings, in which:
FIG. 1 is a schematic diagram illustrating a high-purity chlorine
dioxide gas production device, according to an embodiment of the
present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
FIG. 1 is a schematic diagram illustrating a high-purity chlorine
dioxide gas production device (100), according to an embodiment of
the present invention. The device (100) includes a horizontal
generator (4), a blower (7), an induced draft fan (8), a mother
liquid discharge tank (9), a crystallizer feed pump (10), a
circulating pump (11), a heater (12), an evaporation crystallizer
(13), a filtration unit feed pump (14), a filtration unit (15), a
dryer (16), a mother liquid extraction pump (17), a mother liquid
tank (18), a mother liquid return pump (19), and an air compressor
(30). Although the term "mother liquid" is used in this
application, the term "mother liquid" may also be known as "mother
liquor". The sulfuric acid pipe (1) is connected with the
horizontal generator (4). The hydrogen peroxide pipe (2) joins the
sodium chlorate pipe (3) and the pipes are connected to the
horizontal generator (4). The heat source pipe (5) is connected to
the inlet of the horizontal generator (4). The compressed air pipe
(6) is connected to the air compressor (30) and the horizontal
generator (4). The horizontal generator (4) is connected to the
mother liquid discharge tank (9) through a reaction liquid (mother
liquid) discharge pipe (25). The mother liquid discharge tank (9)
is connected with the mother liquid lower circulating pipe (23)
through the inlet/outlet pipe (26) of the crystallizer feed pump.
The mother liquid lower circulating pipe (23) and the mother liquid
upper circulating pipe (24) are connected with the evaporation
crystallizer (13), the heater (12) and the circulating pump (11).
The mother liquid tank (18) is connected to the evaporation
crystallizer (13) and the horizontal generator (4) respectively
through the inlet/outlet pipe of the mother liquid extraction pump
(27) and the inlet/outlet pipe of the mother liquid return pump
(20). The heat source pipe (21) is connected to the inlet pipe of
the heater (12). The filtration unit (15) is connected to the
mother liquid lower circulating pipe (23) through the inlet/outlet
pipe of the feed pump (28) and the filtrate pipe (22) to form a
circulation loop. The filtration unit (15) is connected to the
dryer (16) via the salt cake discharge pipe (29).
In some embodiments, to make the chlorine dioxide preparation
system run smoothly and continuously, a mother liquid discharge
tank (9) with buffer effect and a mother liquid tank (18) are
equipped between the horizontal generator (4) and the evaporation
crystallizer (13). The chlorine dioxide reaction device and the
evaporation crystallization device are relatively separated and
independent.
In some embodiments, to make the reaction liquid of the horizontal
generator (4) enter to the evaporation crystallizer (13), the
reaction liquid discharge pipe (25) and inlet/out pipe (26) of the
crystallizer feed pump are equipped before and after the mother
liquid discharge tank (9). to respectively connect with the
horizontal generator (4) and mother liquid lower circulating pipe
(23). To make the supernatant of the evaporation crystallizer (13)
return to the horizontal generator (4), the mother liquid return
pump (19), extraction pump (17) and corresponding pipeline are
equipped before and after the mother liquid tank (18) and are
respectively connected to the evaporation crystallizer (13) and the
horizontal generator (4).
In certain embodiments, to facilitate the circulation, evaporation
and concentration of the mother liquid, the evaporation
crystallizer (13), heater (12) and circulation pump (11) are
connected in series by the mother liquid lower circulating pipe
(23) and upper circulating pipe (24) to form a circulation
loop.
In an embodiment, to make full use of the salt cake and filtrate
and avoid waste generated, the filtration unit (15) is provided
with filtrate pipe (22) and salt cake discharge pipe (29) to
respectively connect with the mother liquid lower circulating pipe
(23) and dryer (16) to form a filtrate liquid return channel and
salt cake treatment channel.
The invention provides a method for producing high-purity chlorine
dioxide gas by using hydrogen peroxide, sulfuric acid and sodium
chlorate as raw materials to produce chlorine dioxide and drying
the salt cake to produce salt cake powder. The specific steps are
as follows:
Step 1, sulfuric acid enters the horizontal generator (4) through
pipe (1); the reducing agent--hydrogen peroxide is transferred
through pipe (2) and enters the horizontal generator (4) after
being mixed with the sodium chlorate in the pipe (3), chlorine
dioxide gas is generated after the redox reaction.
Step 2, while the raw material enters the horizontal generator (4)
from one end, the reaction liquid after reacted is discharged from
the other end into the mother liquid discharge tank (9) for
storage, and then sent to the mother liquid into the lower
circulating pipe (23) by the crystallizer feed pump (10).
circulation, heating, evaporation and concentration between the
evaporation crystallizer (13) and the heater (12) under the pumping
action of the circulating pump (11); the salt cake in the mother
liquid is concentrated and crystallized and is deposited at the
bottom of the evaporation crystallizer (13) and the lower
circulating pipe (23) and sent to the filtration unit (15) through
the feed pump (14) for filtration, washing and concentration.
Concentrated solid salt cake enters the dryer (16) to produce
sodium sulfate powder with a dryness up to 99.5% (which can be sold
as a byproduct); the filtrate liquid is returned to the mother
liquid circulating pipe (23) via the filtrate liquid pipe (22).
Step 3, the clarified mother liquid in the upper of the evaporation
crystallizer (13) is sent to the mother liquid tank (18) by the
mother liquid extraction pump (17) for buffering, and then sent to
the horizontal generator (4) by the mother liquid return pump
(19).
In some embodiments, the heat source adds to the horizontal
generator (4) through pipe (5) to heat the reaction solution
indirectly, under the small negative pressure condition, the
temperature of the reaction liquid is step increased from
20-30.degree. C. to 80-85.degree. C.; the air is compressed by the
air compressor (30) and then enters the horizontal generator (4)
and stirs the reaction liquid to make the reaction uniform while
releasing and diluting the chlorine dioxide gas; in addition, the
blower (7) blows the air into the horizontal generator (4) for
further diluting the chlorine dioxide gas concentration to 4-9%
(V/V); the diluted chlorine dioxide gas is sent out to the end use
areas by the induced draft fan (8). The above-mentioned process can
avoid the violent reaction during the preparation process and high
concentration of chlorine dioxide, thus to avoid CIO.sub.2
decomposition, as well as avoid the salt cake crystallization in
the horizontal generator (4) due to the high reaction temperature
and excess water evaporation. The achieved chlorine dioxide gas has
a moisture content of less than 8% (w/w) and is substantially free
of chlorine.
In some embodiments, to increase the evaporation efficiency and
save heat source, the temperature in the evaporation crystallizer
is controlled at 70-73.degree. C. And the vacuum is controlled at
-79 to -81 KPa (g).
The invention provides a method and devices for producing
high-purity chlorine dioxide gas, which have the following
advantages and effects:
The invention describes a device for producing high-purity chlorine
dioxide gas, a mother liquid discharge tank (9) and a mother liquid
tank (18) are equipped between the horizontal generator (4) and the
evaporation crystallizer (13), make the chlorine dioxide reaction
device and the evaporation crystallization device relatively
separated and independent. Meanwhile, the mother liquid discharge
tank (9) and the mother liquid tank (18) play a role in buffering,
so that the chlorine dioxide preparation system can be continuously
and smoothly running.
A method described in the invention, by which the chlorine dioxide
gas is produced with high purity, is using the hydrogen peroxide,
sulfuric acid and sodium chlorate as raw materials and adopting a
horizontal generator, the reaction liquid is heated step by step
from 25.degree. C. to 85.degree. C. under a small negative pressure
condition, which can effectively avoid salt cake crystallization in
the generator due to excessive evaporation of the reaction liquid
and blocking the generator, as well as to avoid chlorine dioxide
decomposition due to the violent reaction, and the prepared
chlorine dioxide gas has a moisture content less than 8% (w/w) and
essentially free of chlorine; the blower (7) blows the air into the
horizontal generator (4) to dilute the chlorine dioxide gas
concentration to 4-9% (V/V) to ensure the chlorine dioxide is
stable and not decomposed easily. The by-product salt cake can be
concentrated and crystallized by controlling the temperature in the
evaporation crystallizer at 70-73.degree. C. and the vacuum degree
at -79 to -81 KPa (g) to produce sodium sulfate powder after being
filtered and dried. The filtrate liquid returns to the mother
liquid lower circulating pipe (23) through pipe (22), no solid and
liquid wastes produced.
This invention will be described in detail below with reference to
the accompanying drawings and embodiments. The described
embodiments are merely some but not all of the embodiments of this
invention. All the other embodiments obtained by the technical
person in this field based on the embodiments of this invention
without creative efforts shall fall within the protection scope of
the present invention.
Example 1
As shown in FIG. 1, devices for producing high-purity chlorine
dioxide gas include a horizontal generator (4), blower (7), induced
draft fan (8), mother liquid discharge tank (9), crystallizer feed
pump (10), circulating pump (11), heater (12), evaporation
crystallizer (13), filtration unit feed pump (14), filtration unit
(15), dryer (16), mother liquid extraction pump (17), mother liquid
tank (18), mother liquid return pump (19), air compressor (30). The
sulfuric acid pipe (1) is connected with the horizontal generator
(4); the hydrogen peroxide pipe (2) joins the sodium chlorate pipe
(3) and are connected to the horizontal generator (4); the heat
source pipe (5) is connected to the inlet of the horizontal
generator (4); the compressed air pipe (6) is connected to the air
compressor (30) and the horizontal generator (4); the horizontal
generator (4) is connected to the mother liquid discharge tank (9)
through a reaction liquid (mother liquid) discharge pipe (25); the
mother liquid discharge tank (9) is connected with the mother
liquid lower circulating pipe (23) through the inlet/outlet pipe
(26) of the crystallizer feed pump; mother liquid lower circulating
pipe (23) and upper circulating pipe (24) are connected with the
evaporation crystallizer (13), heater (12) and the circulating pump
(11); the mother liquid tank (18) is connected to the evaporation
crystallizer (13) and the horizontal generator (4) through the
inlet/outlet pipe of the mother liquid extraction pump (27) and the
inlet/outlet pipe of the mother liquid return pump (20); the heat
source pipe (21) is connected to the inlet pipe of the heater (12);
the filtration unit (15) is connected to the mother liquid lower
circulating pipe (23) through the inlet/outlet pipe of the feed
pump (28) and the filtrate pipe (22) to form a circulation loop;
the filtration unit (15) is connected to the dryer (16) via the
salt cake discharge pipe (29).
Step 1, sulfuric acid enters into the horizontal generator (4)
through pipe (1); the reducing agent--hydrogen peroxide is
transferred through pipe (2) and enters into the horizontal
generator (4) after being mixed with the sodium chlorate in pipe
(3), chlorine dioxide gas is generated after the redox reaction.
The heat source enters the horizontal generator (4) through pipe
(5) to gradually heat the reaction liquid, so that the temperature
of the reaction liquid is increased from 20.degree. C. to
80.degree. C. The air is compressed by the air compressor (30) and
then enters into the horizontal generator (4) and stirs the
reaction liquid to make the reaction uniform while releasing and
diluting the chlorine dioxide gas; in addition, the blower (7)
blows the air into the horizontal generator (4) for further
diluting the chlorine dioxide gas concentration to 4% (V/V); the
diluted chlorine dioxide gas is sent out to the end use areas by
the induced draft fan (8). The product has a moisture content of
7.8% (w/w) and is essentially free of chlorine.
Step 2, while the raw material enters into the horizontal generator
(4) from one end, the reacted reaction liquid is discharged from
the other end of the horizontal generator to the mother liquid
discharge tank (9) for storage, and then sent to the mother liquid
lower circulating pipe (23) by the crystallizer feed pump (10), and
circulation, heating, evaporation and concentration between the
evaporation crystallizer (13) and the heater (12) under the pumping
action of the circulating pump (11); the temperature in the
evaporation crystallizer is controlled at 73.degree. C., the vacuum
degree is controlled at -79 KPa(g). The salt cake in the mother
liquid is concentrated and crystallized and is deposited at the
bottom of the evaporation crystallizer (13) and the lower
circulating pipe (23) and sent to the filtration device (15)
through the feed pump (14) for filtration, washing and
concentration. The concentrated solid salt cake is introduced into
the dryer (16) to produce sodium sulfate powder with dryness up to
99.6% (which can be sold as a byproduct); the filtrate liquid is
returned to the mother liquid circulating pipe (23) via the
filtrate pipe (22) for recycling. No solid and liquid wastes
produced throughout the production process.
Step 3, the clarified mother liquid in the upper of the evaporation
crystallizer (13) is sent to the mother liquid tank (18) by the
mother liquid extraction pump (17) for buffering, and then sent to
the horizontal generator (4) by the mother liquid return pump
(19).
Example 2
As shown in FIG. 1, devices for producing high-purity chlorine
dioxide gas includes a horizontal generator (4), blower (7),
induced draft fan (8), mother liquid discharge tank (9),
crystallizer feed pump (10), circulating pump (11), heater (12),
evaporation crystallizer (13), filtration unit feed pump (14),
filtration unit (15), dryer (16), mother liquid extraction pump
(17), mother liquid tank (18), mother liquid return pump (19), air
compressor (30). The sulfuric acid pipe (1) is connected with the
horizontal generator (4); the hydrogen peroxide pipe (2) joins the
sodium chlorate pipe (3) and are connected to the horizontal
generator (4); the heat source pipe (5) is connected to the inlet
of the horizontal generator (4); the compressed air pipe (6) is
connected to the air compressor (30) and the horizontal generator
(4); the horizontal generator (4) is connected to the mother liquid
discharge tank (9) through a reaction liquid (mother liquid)
discharge pipe (25); the mother liquid discharge tank (9) is
connected with the mother liquid lower circulating pipe (23)
through the inlet/outlet pipe (26) of the crystallizer feed pump;
mother liquid lower circulating pipe (23) and upper circulating
pipe (24) are connected with the evaporation crystallizer (13),
heater (12) and the circulating pump (11); the mother liquid tank
(18) is connected to the evaporation crystallizer (13) and the
horizontal generator (4) through the inlet/outlet pipe of the
mother liquid extraction pump (27) and the inlet/outlet pipe of the
mother liquid return pump (20); the heat source pipe (21) is
connected to the inlet pipe of the heater (12); the filtration unit
(15) is connected to the mother liquid lower circulating pipe (23)
through the inlet/outlet pipe of the feed pump (28) and the
filtrate pipe (22) to form a circulation loop; the filtration unit
(15) is connected to the dryer (16) via the salt cake discharge
pipe (29).
The method for preparing 8t/d chlorine dioxide gas using the above
mentioned device is as follows:
Step 1, sulfuric acid enters the horizontal generator (4) through
pipe (1); the reducing agent--hydrogen peroxide is transferred
through pipe (2) and enters the horizontal generator (4) after
being mixed with the sodium chlorate in pipe (3), chlorine dioxide
gas is generated after the redox reaction. The heat source enters
into the horizontal generator (4) through pipe (5) to gradually
heat the reaction liquid, so that the temperature of the reaction
liquid is increased from 25.degree. C. to 83.degree. C. The air is
compressed by the air compressor (30) and then enters the
horizontal generator (4) and stirs the reaction liquid to make the
reaction uniform while releasing and diluting the chlorine dioxide
gas; in addition, the blower (7) blows the air into the horizontal
generator (4) for further diluting the chlorine dioxide gas
concentration to 6% (V/V); the diluted chlorine dioxide gas is sent
out to the end use areas by the induced draft fan (8). The product
has a moisture content of 7.8% (w/w) and is essentially free of
chlorine.
Step 2, while the raw material enters into the horizontal generator
(4) from one end, the reacted reaction liquid is discharged from
the other end of the horizontal generator (4) to the mother liquid
discharge tank (9) for storage, and then sent to the mother liquid
lower circulating pipe (23) by the crystallizer feed pump (10), and
circulation, heating, evaporation and concentration between the
evaporation crystallizer (13) and the heater (12) under the pumping
action of the circulating pump (11); the temperature in the
evaporation crystallizer is controlled at 72.degree. C., the vacuum
degree is controlled at -80 KPa(g). The salt cake in the mother
liquid is concentrated and crystallized and is deposited at the
bottom of the evaporation crystallizer (13) and the lower
circulating pipe (23) and sent to the filtration device (15)
through the feed pump (14) for filtration, washing and
concentration. The concentrated solid salt cake is introduced into
the dryer (16) to produce sodium sulfate powder with dryness up to
99.65% (which can be sold as a byproduct); the filtrate liquid is
returned to the mother liquid circulating pipe (23) via the
filtrate pipe (22) for recycling. No solid and liquid wastes
produced throughout the production process.
Step 3, the clarified mother liquid in the upper of the evaporation
crystallizer (13) is sent to the mother liquid tank (18) by the
mother liquid extraction pump (17) for buffering, and then sent to
the horizontal generator (4) by the mother liquid return pump
(19).
Example 3
As shown in FIG. 1, a device for producing high-purity chlorine
dioxide gas includes a horizontal generator (4), blower (7),
induced draft fan (8), mother liquid discharge tank (9),
crystallizer feed pump (10), circulating pump (11), heater (12),
evaporation crystallizer (13), filtration unit feed pump (14),
filtration unit (15), dryer (16), mother liquid extraction pump
(17), mother liquid tank (18), mother liquid return pump (19), air
compressor (30). The sulfuric acid pipe (1) is connected with the
horizontal generator (4); the hydrogen peroxide pipe (2) joins the
sodium chlorate pipe (3) and are connected to the horizontal
generator (4); the heat source pipe (5) is connected to the inlet
of the horizontal generator (4); the compressed air pipe (6) is
connected to the air compressor (30) and the horizontal generator
(4); the horizontal generator (4) is connected to the mother liquid
discharge tank (9) through a reaction liquid (mother liquid)
discharge pipe (25); the mother liquid discharge tank (9) is
connected with the mother liquid lower circulating pipe (23)
through the inlet/outlet pipe (26) of the crystallizer feed pump;
mother liquid lower circulating pipe (23) and upper circulating
pipe (24) are connected with the evaporation crystallizer (13),
heater (12) and the circulating pump (11); the mother liquid tank
(18) is connected to the evaporation crystallizer (13) and the
horizontal generator (4) through the inlet/outlet pipe of the
mother liquid extraction pump (27) and the inlet/outlet pipe of the
mother liquid return pump (20); the heat source pipe (21) is
connected to the inlet pipe of the heater (12); the filtration unit
(15) is connected to the mother liquid lower circulating pipe (23)
through the inlet/outlet pipe of the feed pump (28) and the
filtrate pipe (22) to form a circulation loop; the filtration unit
(15) is connected to the dryer (16) via the salt cake discharge
pipe (29).
The method for preparing 12t/d chlorine dioxide gas using the above
mentioned device is as follows:
Step 1, sulfuric acid enters into the horizontal generator (4)
through pipe (1); the reducing agent--hydrogen peroxide is
transferred through pipe (2) and enters into the horizontal
generator (4) after being mixed with the sodium chlorate in pipe
(3), chlorine dioxide gas is generated after the redox reaction.
The heat source enters the horizontal generator (4) through pipe
(5) to gradually heat the reaction liquid, so that the temperature
of the reaction liquid is increased from 30.degree. C. to
85.degree. C. The air is compressed by the air compressor (30) and
then enters the horizontal generator (4) and stirs the reaction
liquid to make the reaction uniform while releasing and diluting
the chlorine dioxide gas; in addition, the blower (7) blows the air
into the horizontal generator (4) for further diluting the chlorine
dioxide gas concentration to 9% (V/V); the diluted chlorine dioxide
gas is sent out to the end use areas by the induced draft fan (8).
The product has a moisture content of 7.5% (w/w) and is essentially
free of chlorine.
Step 2, while the raw material enters into the horizontal generator
(4) from one end, the reacted reaction liquid is discharged from
the other end of the horizontal generator (4) to the mother liquid
discharge tank (9) for storage, and then sent to the mother liquid
lower circulating pipe (23) by the crystallizer feed pump (10), and
circulation, heating, evaporation and concentration between the
evaporation crystallizer (13) and the heater (12) under the pumping
action of the circulating pump (11); the temperature in the
evaporation crystallizer is controlled at 70.degree. C., the vacuum
degree is controlled at -81 KPa(g). The salt cake in the mother
liquid is concentrated and crystallized and is deposited at the
bottom of the evaporation crystallizer (13) and the lower
circulating pipe (23) and sent to the filtration device (15)
through the feed pump (14) for filtration, washing and
concentration. The concentrated solid salt cake is introduced into
the dryer (16) to produce sodium sulfate with dryness up to 99.6%
(which can be sold as a product); the filtrate is returned to the
mother liquid circulating pipe (23) via the filtrate pipe (22) for
recycling. No solid and liquid wastes produced throughout the
production process.
Step 3, the clarified mother liquid in the upper of the evaporation
crystallizer (13) is sent to the mother liquid tank (18) by the
mother liquid extraction pump (17) for buffering, and then sent to
the horizontal generator (4) by the mother liquid return pump
(19).
It will be readily understood that the components of various
embodiments of the present invention, as generally described and
illustrated in the figures herein, may be arranged and designed in
a wide variety of different configurations. Thus, the detailed
description of the embodiments of the present invention, as
represented in the attached figures, is not intended to limit the
scope of the invention as claimed but is merely representative of
selected embodiments of the invention.
The features, structures, or characteristics of the invention
described throughout this specification may be combined in any
suitable manner in one or more embodiments. For example, reference
throughout this specification to "certain embodiments," "some
embodiments," or similar language means that a particular feature,
structure, or characteristic described in connection with the
embodiment is included in at least one embodiment of the present
invention. Thus, appearances of the phrases "in certain
embodiments," "in some embodiment," "in other embodiments," or
similar language throughout this specification do not necessarily
all refer to the same group of embodiments and the described
features, structures, or characteristics may be combined in any
suitable manner in one or more embodiments.
It should be noted that reference throughout this specification to
features, advantages, or similar language does not imply that all
of the features and advantages that may be realized with the
present invention should be or are in any single embodiment of the
invention. Rather, language referring to the features and
advantages is understood to mean that a specific feature,
advantage, or characteristic described in connection with an
embodiment is included in at least one embodiment of the present
invention. Thus, discussion of the features and advantages, and
similar language, throughout this specification may, but do not
necessarily, refer to the same embodiment.
Furthermore, the described features, advantages, and
characteristics of the invention may be combined in any suitable
manner in one or more embodiments. One skilled in the relevant art
will recognize that the invention can be practiced without one or
more of the specific features or advantages of a particular
embodiment. In other instances, additional features and advantages
may be recognized in certain embodiments that may not be present in
all embodiments of the invention.
One having ordinary skill in the art will readily understand that
the invention as discussed above may be practiced with steps in a
different order, and/or with hardware elements in configurations
which are different than those which are disclosed. Therefore,
although the invention has been described based upon these
preferred embodiments, it would be apparent to those of skill in
the art that certain modifications, variations, and alternative
constructions would be apparent, while remaining within the spirit
and scope of the invention. In order to determine the metes and
bounds of the invention, therefore, reference should be made to the
appended claims.
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